System for determining the load condition of an engine for maintaining optimum engine oil temperature

Abstract

A temperature control system, in a liquid cooled internal combustion engine equipped with a radiator, controls the state of a flow control valve for controlling flow of a temperature control fluid through a passageway in the engine. Sensors detect the engine oil temperature, the temperature of the temperature control fluid, and the ambient air temperature. An engine computer receives signals from the sensors, produces control signals based on the sensor signals, and sends the control signals to the flow control valve to control the state of the valve. A set of predetermined values defining a temperature control curve are utilized to determine the desired state of the valve. An optimum engine oil temperature curve is utilized to determine the temperature state and load condition of the engine. The temperature control curve is adjusted based on the temperature state and/or the load condition of the engine.

I claim: 
     
       1. A temperature control system in a liquid cooled internal combustion engine equipped with a radiator and a water jacket, the system comprising: a flow control valve for controlling flow of a temperature control fluid through the water jacket, the flow control valve having a first state for inhibiting said flow and a second state for allowing said flow;   a first sensor for sensing an actual engine oil temperature and for providing a signal indicative thereof;   a second sensor for sensing an actual ambient air temperature and for providing a signal indicative thereof;   a third sensor for sensing an actual temperature control fluid temperature and for providing a signal indicative thereof;   an engine computer for receiving the actual engine oil temperature, the actual ambient air temperature and the temperature control fluid temperature, the engine computer determining a desired engine oil temperature based on ambient air temperature, the desired engine oil temperature varying as a function of the actual ambient air temperature, the engine computer comparing the actual engine oil temperature to the desired engine oil temperature for determining the temperature state of the engine, the engine computer adjusting a set of predetermined values based on the temperature state of the engine, the set of predetermined values having a temperature control fluid temperature component and an ambient air temperature component, the set of predetermined values defining a curve which determines the state of the flow control valve, the engine computer determining a desired temperature control fluid temperature by comparison of the actual ambient temperature to the adjusted set of predetermined values, the engine computer comparing the actual temperature control fluid temperature to the desired temperature control fluid temperature and controlling the actuation of the flow control valve between its first and second states depending on the comparison of the actual temperature control fluid temperature to the desired temperature control fluid temperature, the flow control valve being in the first state when the actual temperature control fluid temperature is less than the desired temperature control fluid temperature, and the flow control valve being in the second state when the actual temperature control fluid temperature is greater than the desired temperature control fluid temperature.   
     
     
       2. A temperature control system according to claim 1 wherein the engine computer determines an engine load condition based on a comparison of the actual engine oil temperature to the desired engine oil temperature, and wherein the engine computer adjusts the temperature control fluid temperature component of the set of predetermined values in accordance with the load condition. 
     
     
       3. A temperature control system according to claim 1 wherein the engine computer determines an amount that the actual engine oil temperature exceeds the desired engine oil temperature and wherein the engine computer adjusts the temperature control fluid temperature component of the set of predetermined values as a function of the amount of said excess. 
     
     
       4. A temperature control system according to claim 1 wherein the engine computer adjusts the temperature control fluid temperature component of the set of predetermined values downward a preset amount for each one degree that the actual engine oil temperature exceeds the desired engine oil temperature. 
     
     
       5. A temperature control system according to claim 4 wherein the preset amount of adjustment is a value within a range of between about one degree Fahrenheit and about ten degrees Fahrenheit. 
     
     
       6. A temperature control system according to claim 5 wherein the preset amount of adjustment is three degrees Fahrenheit. 
     
     
       7. A temperature control system according to claim 6 wherein the preset amount of adjustment is two degrees Fahrenheit. 
     
     
       8. A temperature control system according to claim 7 wherein the preset amount of adjustment is one degree Fahrenheit. 
     
     
       9. A temperature control system according to claim 1 wherein the engine computer adjusts the temperature control fluid temperature component of the set of predetermined values downward a preset amount for each three degrees Fahrenheit that the actual engine oil temperature exceeds the desired engine oil temperature. 
     
     
       10. A temperature control system according to claim 1 wherein the engine computer adjusts the temperature control fluid temperature component of the set of predetermined values downward a preset amount for each five degrees Fahrenheit that the actual engine oil temperature exceeds the desired engine oil temperature. 
     
     
       11. A temperature control system according to claim 1 wherein the engine computer determines a rate of change of the actual engine oil temperature and wherein the engine computer adjusts the temperature control fluid temperature component of the set of predetermined values as a function of the rate of change. 
     
     
       12. A temperature control system according to claim 11 wherein the adjusting of the temperature control fluid temperature component of the set of predetermined values varies linearly with the rate of change of the actual engine oil temperature. 
     
     
       13. A temperature control system according to claim 11 wherein the adjusting of the temperature control fluid temperature component of the set of predetermined values varies nonlinearly with the rate of change of the actual engine oil temperature. 
     
     
       14. A temperature control system according to claim 1 wherein the engine computer determines an adjustment factor for adjusting the temperature control fluid temperature component of the set of predetermined values, the adjustment factor varying as a function of ambient air temperature, and wherein the engine computer adjusts the temperature control fluid temperature component of the set of predetermined values according to the adjustment factor. 
     
     
       15. A temperature control system according to claim 14 wherein the adjustment factor varies linearly with ambient air temperature. 
     
     
       16. A temperature control system according to claim 14 wherein the adjustment factor varies nonlinearly with ambient air temperature. 
     
     
       17. A temperature control system according to claim 1 wherein the engine includes an intake manifold and wherein the engine computer receives signals from the intake manifold indicative of an intake manifold vacuum pressure, and wherein the engine computer determines an engine load condition based on the intake manifold vacuum pressure and adjusts the temperature control fluid temperature component of the set of predetermined values in accordance with the load condition. 
     
     
       18. A temperature control system according to claim 17 wherein the engine load condition is a high load condition when the intake manifold vacuum pressure is less than about 4 inches Hg and wherein the engine computer adjusts the temperature control fluid temperature component of the set of predetermined values downward a first preset amount. 
     
     
       19. A temperature control system according to claim 17 wherein the engine load condition is an extremely high load condition when the intake manifold vacuum pressure is less than about 2 inches Hg and wherein the engine computer adjusts the temperature control fluid temperature component of the set of predetermined values downward a second preset amount. 
     
     
       20. A temperature control system in a liquid cooled internal combustion engine equipped with a radiator and a water jacket, the system comprising: a flow control valve for controlling flow of a temperature control fluid through the water jacket, the flow control valve having a first state for inhibiting said flow and a second state for allowing said flow;   a first sensor for sensing an actual engine oil temperature and for providing a signal indicative thereof;   a second sensor for sensing an actual ambient air temperature and for providing a signal indicative thereof;   a third sensor for sensing an actual temperature control fluid temperature and for providing a signal indicative thereof;   means responsive to the actual ambient temperature signal for determining a desired engine oil temperature based on the actual ambient temperature, the desired engine oil temperature varying as a function of the actual ambient temperature;   means for comparing the actual engine oil temperature to the desired engine oil temperature;   means for determining an engine load condition based on the comparison of the actual engine oil temperature to the desired engine oil temperature;   means for determining a desired temperature control fluid temperature;   means for determining an adjustment factor as a function of the engine load condition;   means for adjusting the desired temperature control fluid temperature in accordance with the determined adjustment factor;   means for comparing the actual temperature control fluid temperature to the adjusted desired temperature control fluid temperature for determining a desired state of the flow control valve; and   means for actuating the flow control valve into the desired state.   
     
     
       21. A method for controlling the state of a flow control valve in an internal combustion engine, the flow control valve controlling flow of temperature control fluid through a passageway and having a first state for inhibiting the flow of temperature control fluid through the passageway and a second state for permitting the flow of temperature control fluid through the passageway, the method comprising the steps of: (a) measuring an actual engine oil temperature;   (b) measuring an actual ambient air temperature;   (c) measuring an actual temperature control fluid temperature;   (d) determining a desired engine oil temperature value for the actual ambient air temperature, said desired engine oil temperature value varying as a function of the ambient air temperature;   (e) comparing the actual engine oil temperature to the desired engine oil temperature value;   (f) determining a desired temperature control fluid temperature from the actual ambient air temperature, the desired temperature control fluid temperature varying as a function of the ambient air temperature;   (g) adjusting the desired temperature control fluid temperature based on the comparison of the actual engine oil temperature to the desired engine oil temperature value;   (h) comparing the actual temperature control fluid temperature to the adjusted desired temperature control fluid temperature; and   (i) actuating the flow control valve so as to place said valve in its first state when the actual temperature control fluid temperature is less than the adjusted desired temperature control fluid temperature, and actuating the valve to place it in its second state when the actual temperature control fluid temperature is greater than the adjusted desired temperature control fluid temperature.   
     
     
       22. A method for controlling the state of a flow control valve according to claim 21 wherein said first state inhibits fluid flow to the radiator. 
     
     
       23. A method for controlling the state of a flow control valve according to claim 21 wherein said first state permits flow to the intake manifold. 
     
     
       24. A method for controlling the state of a flow control valve according to claim 21 wherein the adjusting of the temperature control fluid temperature comprises the steps of: determining the amount that the actual engine oil temperature exceeds the desired engine oil temperature;   determining an adjustment factor for adjusting the desired temperature control fluid temperature based on the amount of said excess; and   combining the adjustment factor and the desired temperature control fluid temperature to form the adjusted desired temperature control fluid temperature.   
     
     
       25. A method for controlling the state of a flow control valve according to claim 21 wherein the adjusting of the temperature control fluid temperature component comprises the steps of: determining a rate of change of the actual engine oil temperature with respect to the desired engine oil temperature;   determining an adjustment factor for adjusting the desired temperature control fluid temperature based on the rate of change of the actual oil temperature; and   combining the adjustment factor and the desired temperature control fluid temperature to form the adjusted desired temperature control fluid temperature.   
     
     
       26. A method for controlling the state of a flow control valve according to claim 21 wherein the adjusting of the temperature control fluid temperature component comprises the step of: determining an adjustment factor for adjusting the desired temperature control fluid temperature based on the actual ambient air temperature, the adjustment factor varying as a function of at least ambient air temperature; and   combining the adjustment factor and the desired temperature control fluid temperature to form the adjusted desired temperature control fluid temperature.   
     
     
       27. A method for controlling the state of a flow control valve in an internal combustion engine, the flow control valve controlling flow of temperature control fluid through a passageway and having a first state for inhibiting the flow of temperature control fluid through the passageway and a second state for permitting the flow of temperature control fluid through the passageway, the method comprising the steps of: (a) measuring an actual engine oil temperature;   (b) measuring an actual ambient air temperature;   (c) measuring an actual temperature control fluid temperature;   (d) determining a desired engine oil temperature value for the actual ambient temperature, said desired engine oil temperature value varying as a function of the ambient air temperature;   (e) comparing the actual engine oil temperature to the desired engine oil temperature value;   (f) determining an adjustment factor based on the comparison of the actual engine oil temperature to the desired engine oil temperature;   (g) combining the adjustment factor with at least one temperature control fluid temperature component of a set of predetermined values having temperature control fluid temperature component and an ambient air temperature component, the combination forming an adjusted temperature control fluid temperature component;   (g) determining a desired state of the flow control valve by comparing the actual temperature control fluid temperature to the adjusted temperature control fluid temperature component and comparing the actual ambient air temperature to the ambient air temperature component of the set of predetermined values; and   (h) actuating the valve so as to place it in the desired state.   
     
     
       28. A method for controlling the state of a flow control valve according to claim 27 wherein the set of predetermined values defines a curve, at least a portion of the curve having a non-zero slope. 
     
     
       29. A method for controlling the state of a flow control valve according to claim 27 wherein the adjustment factor varies as a function of ambient air temperature. 
     
     
       30. A method for controlling the state of a flow control valve according to claim 27 wherein the determination of the adjustment factor further comprises the steps of: determining the amount that the actual engine oil temperature exceeds the desired engine oil temperature; and   determining an adjustment factor based on the amount of excess.   
     
     
       31. A method for controlling the state of a flow control valve according to claim 27 wherein the determination of the adjustment factor further comprises the steps of: determining a rate of change of the actual engine oil temperature with respect to the desired engine oil temperature; and   determining an adjustment factor based on the rate of change of the actual oil temperature.   
     
     
       32. A method for controlling the flow of temperature control fluid in an internal combustion engine comprising the steps of: measuring an actual engine oil temperature;   measuring an actual ambient air temperature;   measuring an actual temperature control fluid temperature;   determining a desired engine oil temperature value from the actual ambient temperature, the desired engine oil temperature value varying as a function of the ambient air temperature;   comparing the actual engine oil temperature to the desired engine oil temperature value;   providing a temperature control curve defining the flow of temperature control fluid through the internal combustion engine, the temperature control curve having temperature control fluid temperature components and ambient air temperature components;   adjusting the temperature control curve based on the comparison of the actual engine oil temperature to the desired engine oil temperature value;   comparing the actual temperature control fluid temperature and the actual ambient air temperature to the adjusted temperature control curve; and   controlling the flow of temperature control fluid based on the comparison of the actual temperature control fluid temperature and the actual ambient temperature to the adjusted temperature control curve.